Medical X-ray imaging of patients, for example angiography, is most important and a frequently used examination method. Angiography is a radiological method for examination of blood or lymph vessels. Blood has the same radiodensity as the surrounding tissues and a radiocontrast agent (which absorbs X-rays) is therefore added to the blood to make angiography visualization possible. A catheter is inserted into the vessel, e.g. by Seldinger technique, and a water soluble contrast agent is injected into the vessel, after which a series of X-ray images of the vessel is taken. Examinations of arteries, veins and lymph vessels are denoted arteriography, flebography and lymphography, respectively. Arteriography is a commonly applied examination method and includes angiocardiography for examination of the heart, coronary angiography for examination of the coronary arteries of the heart and aortography for examination of the aorta.
The X-ray images may be taken as either still images displayed on a fluoroscope, or may be taken as motion images. Fluoroscopy requires high concentrations of contrast agents, for example iodinated contrast agents. Fluoroscopy involves the use of ionizing radiation and all fluoroscopic procedures therefore pose a potential health risk to the patient. Radiation doses that the patient is exposed to depend greatly on the size of the patient as well as length of the procedure and exposure times vary depending on the procedure being performed.
The International patent publication WO 2005/094688, assigned to the same applicant as the present application and the contents of which is hereby incorporated by reference, describes an arrangement for obtaining imaging data. Although the invention described in this document provides improvements within the field of imaging, there is still a need for further improvements in obtaining images of an object at high repetition rate.
The examination of blood or lymph vessels in angiography is a time-dependent process, which puts requirements on the repetition rate of the detector used. When performing angiography it is therefore important to rapidly obtain the images. Further, in angiocardiography it is important to take the motion of the heart into consideration.
In view of the above, it would be desirable to provide improvements within the field of medical imaging and in particular angiography.